One of the strongest and cleanest-looking joints to use when butting boards together for a table top is a dowel joint. For the best results, use precut dowels made out of maple, with spiral grooves to let air in and excess glue out when inserting the dowel. For a perfectly flat surface, start with boards of the same thickness, and use a self-centering doweling jig to drill the dowel holes precisely on the centerline along the edge of the boards.
Things You'll Need
- Steel measuring tape
- Carpenter’s square
- Metal drill stop
- Wood drill bit
- 1 1/2-inch grooved maple dowels
- Hex wrench
- Self-centering doweling jig
- Cordless drill/driver
- Slow drying wood glue
- Plastic mallet
- Hardwood block
- Adjustable bar clamps
Measure and mark the dowel positions on the joint edges of all boards with a steel measuring tape, a sharp pencil and a carpenter’s square. Space the marks evenly and precisely across the board 6 to 8 inches apart, and position the end marks 1/2 inch from the end.
Place the boards on a flat surface and sort the boards as desired to arrange the ideal grain pattern of the table top. Mark each individual board on the mating board edge with consecutive numbers to retain the grain pattern during the doweling process.
Grip the first board in a carpenter’s vice with the numbered edge uppermost. If you only have an engineer’s vice, straddle the board with two strips of scrap wood between the vice jaws to prevent surface marks.
Slide a metal drill stop onto a drill bit approximately one-third to one-half the thickness of the table top. Size the drill bit to coincide with the diameter of the 1 1/2-inch-long dowels you intend to use. Position the drill stop 3/4 inch from the end of the drill lands – not from the tip of the bit – and tighten the Allen head screw on the drill stop with a hex wrench.
Straddle the numbered edge of the board with a self-centering doweling jig. Slide the jig sideways until the centerline on the corresponding drill guide hole lines up precisely with the centerline of the first dowel position. Clamp the doweling jig firmly in place.
Fit the drill bit into a cordless drill/driver, insert the bit into the correct guide hole in the doweling jig, and drill the first dowel hole to the required depth. Repeat by resetting the doweling jig and drilling all the remaining dowel holes into the numbered joint edges of the rest of the boards the same way.
Remove any trapped sawdust from the holes and insert dowels into the edges of all the odd-numbered board edges that you marked in Step 2, as follows: Squeeze a small amount of slow-drying wood glue into the dowel holes, and apply a thin coat of glue to the sides of the dowels. Insert the dowels and tap them firmly all the way down with a plastic mallet. Wipe off all excess glue with a damp rag.
Squeeze a little wood glue into all the remaining holes in the second even-numbered board. Apply a thin coat of glue to both flat joint surfaces and the sides of the dowels. Fit the boards together by matching dowels with corresponding holes.
Stand the first two joined boards edge up on a firm surface. Place a hardwood block on the top edge close to the center dowel hole. Tap the dowel joints evenly together with a hammer all the way outward along both sides until there are no gaps left between the joint.
Work quickly and continue gluing the rest of the boards together the same way. Once joined, clamp the boards firmly together with several adjustable bar clamps spaced evenly across both the top and bottom surfaces of the table top. Wipe off excess glue with a damp rag.
Lay the clamped table top flat on the floor and allow 24 hours for the glue to cure before sanding and finishing the top.
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